<style>
    .box1 {
        width: 0;
        height: 0;
        /* 把上边框宽度调大 */
        /* border-top: 100px solid transparent;        
        border-right: 50px solid skyblue; */
        /* 左边和下边的边框宽度设置为0 */
        /* border-bottom: 0 solid blue;        
        border-left: 0 solid green; */
        /* 1.只保留右边的边框有颜色 */
        border-color: transparent red transparent transparent;
        /* 2. 样式都是solid */
        border-style: solid;
        /* 3. 上边框宽度要大， 右边框 宽度稍小， 其余的边框该为 0 */
        border-width: 100px 50px 0 0;
    }
    .box2{
        width: 0;
        height: 0;
        border-color: transparent pink transparent transparent;
        border-style: solid;
        border-width: 100px 50px 0 0 ;
    }
</style>
</head>

<body>
    <div class="box1"></div>
    <div class="box2"></div>
</body>
